SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd71689edf4808997e6fb1bcc4ead4205a7d450e187ab671c022039789116d352' 
  AND token = 'W+LoM0x7T/l3J0Fzt/V5ZIcYCavwwdUnJEfxtPIeZhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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