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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4e84106a38f5ae7dc2c23d309d01b24da7d623130f87f5e78da7e866ae70fdb' 
  AND token = 'RMcj3Ha/gq4BoNGw7qqOnfkXqVdhbDc8XxKnGS+0Xz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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