SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8508a2648139fafb7bed66717c3735df57a5d776cd5e6306bce13060efe1c24' 
  AND token = 'GdOgU+VYB/lnmtNvX5klJDqPB+WOX+wjKeHV80KLE1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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