SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7db543ababecd79a38732834babf8ceaafd464b0290b58324e321ccf87f304e' 
  AND token = 'ekB9TQxFZGSjWRs8Y6FGVssKtjMSYsnZ2hinHSLn2HE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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