SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b37ac3a036e886b42b1ca997b7076e84a80a4fd7e4a08457590c032785c55ba' 
  AND token = 'DijJYrYArqheeYMjrNb+PoMRjpqJklPTMtlrtGL28BY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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