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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cf4e4c5b52f3b6dfeadb7958f42e4e4fe75d08cf43e1cf4a46edc912781d02a' 
  AND token = 'Gyuy6WqPsUUkxsLzUU1QBJd53K0QTBlgmhxCMDJUXmI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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