SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b2122d0b42d373cf794465eac79f6b9baa52871b981098bc2cf8f67a0d83bc' 
  AND token = 'bJKSwkrVyARW+hthEXbwRIORo2QnHgnJA1YehxZpw6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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