SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a66a6db80de48825734c05176a26637fa8779bcde5fbb16c3589f0dda00869f5' 
  AND token = 'JX6lthB+RbIKlX2LTdPy7nA9iVLetQP45ZbxvSQ33s8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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