SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '713d297b6b5d16360fc274cb1b67463924292d63f5045baba812e009ebc9f073' 
  AND token = 'xpajpwLmlj6oD38rWhGvq2VgJUrpvYmh54ZgDuyjHyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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