SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db0e56b132a62f1ecba5ce9fe4a511406443b8335ada4cafbdde29e3bc8d11c1' 
  AND token = 'cqYrDOcfyp61wywpXJB+lN3M9rBUp2ufPPmo8EW4ZZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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