SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '256f1fe43d4fafb83f2f68cf3aeefc09a91260f6ea01d13b92021657ee8de143' 
  AND token = 'YCE3rzuGXg3MOfsTGrybCth2pAnOfFjaqgSFqWo16iE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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