SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33172a6dfee7a878aa83403cfc5c2eeaab401b0242291c18746eb2debb70f8ce' 
  AND token = 'MhPH+Tj8JINVj0WGGbYpEMeyOKzXCad/vRGVi0GERr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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