SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a274e52cbaea58537254e18683813d494cd845688c0fe28888b1df15152c997' 
  AND token = 'o8s2i2tTxQ2Rp+4d23/71jMfzP2jkrm9eQMF/syZwGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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