SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239a855466b99193730c333378aadc95f708e581cd690b3d2d7a34f94844936d' 
  AND token = 'wmzJYNIJqmxdNMsUknFAQ2LiPTLRRnb9YpsnLIE5VU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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