SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '093c7966f5d9f30238e09142c511cd62ad1ec7c815e2b311ba6eba8f7f8d6912' 
  AND token = 'kxxUhLoG4H2Y0RKGLnX3xIZy+LhBy5UoifsSmqjGH48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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