SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20352fb851381edbc575aafc61f7a9643196afb576d3205ea760c2824eb267a9' 
  AND token = 'xeS+SRFsOLVniSwEqOeleyXnJxBjObiMqHpGqrxlFyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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