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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f71b9efe3f81b6ce337a7d1b3a78ebb06f1dc5cfc7e8a7efccb4feb8fad76e4d' 
  AND token = '9ug4sJjH3hQ/U3FLYROcd2nfW6CbyXZRhmtu8JxBZMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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