SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ec91f4612f203f2caf2bad9cc1fdc90656a2c9af6c20a826c38a98fac7c91cf' 
  AND token = 'W7bQASynUw0UKRVtn+Bt02mk8QAiqjJe8qDgcRH3+nU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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