SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ce56cdc8d4291c3f278eed0d1a556c42b92e8917bf9beabb81b82bd316207f3' 
  AND token = 'KxU3mv515GOV/SmoHHsRQXGRP1+MCzqXH83AHdXxqg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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