SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e51d388a5b1bcf83e4604acc99bdaf4068225eb1741653c87cbb52f16b9000' 
  AND token = 'zvn+TCv/UH7hWW7mFnzxN3jVGKq50HCL9XkLS0BewsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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