SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b43e6aa2d31ee11a34dffbb0f90266c56bbe6a98a0e1f585f0326af440cc0b44' 
  AND token = 'gcnmUu6Bdk27v022DuqHKXMJg4wCL0pP2YHHwHzHkBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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