SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2b70fe369c6bcbc7d36db37355dfa5c45e0b78b023820a8e1b34bce8c42883b' 
  AND token = 'O1a0Uj/xIHlRRCM9BaJsmfzydX0h4DAqyn7qO2tcWhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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