SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0db12b7113080b10beaf07e00163c3a2037b4922dccc326e8ca73cee256c9b1' 
  AND token = 'GR4jXOAcyLf3u71gnVyOggA2A7+8FFivAhl6rBFRDvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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