SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f2a6473d5f6e6888f57282eabda3aeb1a270a7c80d37418f0765a7c959ec1a' 
  AND token = 'hGJ8wzoiDedNB9NzxChHH6DDzbU74nMjvWwZK6jRaOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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