SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '243be38e436e2833aabab4508a6f5c2904f1c1a2339a6485129529dbbd23c356' 
  AND token = 'g+YPWbMDI1QR/AIgPKPAsKROJh7fUYcntq8nglLJoPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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