SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b274fb5cd850e111c4c58deb57506e411c6d0c8f5220c3667548d476478dac01' 
  AND token = 'TYMRgRcOliUpQ9sEnVFbb+rsTfyCGoJdAjIntN4Dpy0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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