SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0d1cd233abac0bb9d5996509edea2c46b9dbf3eaaea01b682b71811dc4c5b67' 
  AND token = 'hePx3NePFj5ZvystoC48JTSZZrpOV7YZ1rjSKoTeqhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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