SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '645b181c74da2348ca4f67da2e40ae389185fcaad0968f759e0303822f5998b0' 
  AND token = 'KmUnCGdOsqbQGO7bRYy3rtcSuSlmbODqhCNu21vpKjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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