SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3378618e10b40431b27e1d25a3d56a573987c14fad40455898b712951748cbfe' 
  AND token = 'k22L4SXVekLYw3LZYTEtWddSM6DiwJaSLb3z3iy9BqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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