SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76003aa5597805ed273780f3e18c76f3809299516d1cf4b7fa61970611a186a1' 
  AND token = 'S5pLDOJRQYz+BDQNRIjkN6XuFb9QadsPKkzPqxw/FP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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