SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82b868128f9b2a31f5c262e49e6f5adae175762d1a0bababcbcdf5e175162d74' 
  AND token = 'YPmEJsvMq6pywpJwRcZjTTsjP/KINjdUCURFsiwvqpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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