SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef8ac8b98b826dbdded2cd1f59ad747e2340bcf25acacb1f9cf8675eda6a2a17' 
  AND token = 'FH1yEqsy13Gab7IrExaSl6k5wzLtPGoryVQ+NR6YIA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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