SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a282e3fe8ca641802b88257771e1484fb9311c01993557db415b48ce8244cbc9' 
  AND token = 'yek71kTfV1XZEsy6WfA6VK47t19uPSDIfjrcniqOADQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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