SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f59ef21ca35f3dc2078c9bbcf321a2397d4a59a699df08ea1bc64cd670fc2ff0' 
  AND token = 'B1MDt6dUG4NXM5NHfjRn1J0DGbbBjHucxOgULWTa1CM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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