SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a9abe68963839152d8faddcbc56c20c81cae06292d017dd6b7e146db7e286f7' 
  AND token = 'GWTgvGos/+D8lAtEi/Mvk4xsPNXVAV49ALsbioXeQbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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