SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e68fe9803e0f2efddf2b5fd54b722ef54e1301375a920fa1119c1b31605042d' 
  AND token = '12NfMKPD5GhZZf38IyppElo8bSZhF0oqZnpiikmQwws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}