SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be566258e0990c924f75fcf7777aca9a34b2188a816adb41f20c968fdbc60e8c' 
  AND token = 'bkwhbr/040tf5Snqk6Dx95RAWXQGZH34iglVMJr+r50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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