SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe4762926db5ed4dc1dc9ed351921b69c327c8047f357706723cb44508517fe' 
  AND token = '3CQBdUqMSOnVcvjt/Nvcc8HOpraTgwb+b38eaVDxV1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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