SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b81607719e4e81ce86c1344df1ac14711cade2444219cea7a39a02a2909648a' 
  AND token = 'CKsRIpyI4stAdPEVvshLQ+Ayh7UIfKE2uUAHJDipkPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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