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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6648b6fef4a82d559db6d463a20c9b15408a7e00c45e8c3f3eaaa78a17b21d7a' 
  AND token = 'FV+9pL6BPpPiTL/EWR0Mw1BbbaZfuMMorgQ6XFxfjbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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