SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20014a0a39d66efa295e9e3c84b6752323e99fc831a27371a5b615a7943bac20' 
  AND token = 'F4hILmeHI9K26SoN9q9zSg/D1fbQRgspT2EuxEJJhwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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