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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9b7b1428ddb9cb02d54ece23f435b4ad7d6abd8c911e98d396df2dafe879b73' 
  AND token = 'bt+Fd8uFzU50fzTW0yc4XLd9rUgNY9G/W6ev5e+1qNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}