SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b2c3a1fa24284a78f8a73e73b675f610374880e9b1da05b32bd129ebfb50bf1' 
  AND token = 'qbWJWIqXukDMOhpQMjayW1Y8UfiFyXf0KrB9VlY+/L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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