SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a3fa88869ded2a1088e91caa66cb33bd50c92c6702ecec7d7371a320d67b611' 
  AND token = 'S12pN74tazKS28PhAnGQ8BizL04qAkfK1QZeRT1ae1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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