SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5c12c12aaa250b53f81048a266538b5e96ee761e08e034bfc3cdf72bae5fd81' 
  AND token = 'FSp6S1CeuZgiLwxpkROEiT4RvUsmm9JmNipOCKEcgbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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