SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a0502f57ec29a9c3232f0aec395d42c1c5feeea45e081295ae474a3934593f3' 
  AND token = 'o4k9oHshiZEVr7hm9JUPMBjGeMt7Ybav2x/JLiCCVlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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