SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8790a638670060e38002f568edb5566fa85e48517163e57796b709cb2d309b9e' 
  AND token = 'WAQ9CExijjPG80QpyQQkEG7ZrljXAuIJB3Y4VzsA2kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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