SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2c7fecd9d1705f54a47c432bc9aa383e8766ffc21e2931f87be047ae26e1b349' 
  AND token = '/vV4n4DrkxRhm613XQduOQicfZwusLqF6d9u0cDKxFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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