SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f81548352774ed8f8c0221f51265a1b3829762087be30422ebe2ffea0ce294f' 
  AND token = 'VrgnQUTCTNSnyJ2g2pu98yjQ4eoRsY9VuK1HWBN+T5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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