SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8dc1fcf1916433e46a065a621fdba0fdfcf43479c5ef56ec0a976af65280763' 
  AND token = 'Z2//FyQGYHnng2FvoXdFaclDDqxusVKt8bYysZZCfQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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