SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a87913844e734bee030078bdf3b29c5a1366f48a9be55b0c4512a9055417d2' 
  AND token = 'EUOk7bc2+SN62Lch0KWrU0lNWayXTJcLpkUwiDEKQKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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