SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b506780aeffc245129bed421393b605ca5f7996a0f692739266aa490c91eba7' 
  AND token = 'bVd4YhVPFAZ4RsUjNGJoMf292zs/ZGY+VvAHpOPT9cI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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