SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be4b23c4b337ab44ad510817d2298af238df8b39f4461561c24364ee7d4b1bde' 
  AND token = 'wk7dGdfJPCo8vCuBtT+q/pYnUrRzFDPgWpVm5JIWRUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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