SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b04ad834c7b05c18094156625c77900bbc834e06886ee8c55318ec6ecbf74da3' 
  AND token = 'NaKsZugpSfngw+LrsApcNUXw/OBwf7cBcXWQhgWsOvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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