SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a900295bbe73e3ed00d1f95cf08594a4c17cf741ae76341736b9d4eb284f5104' 
  AND token = 't+ClDVoq62QTnnWKRiYOp7ElFXbFkLRuHtz2ehn0SXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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