SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54ab2a397cbbf98f57836af58cc59688c2c6d80c6ce9537308b51e61cbcfc08a' 
  AND token = 'NnCXt2jF+YscJjhEHUBR3/wBZK2TX+l1Vg3OQZB8P4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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