SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b8f87aabb6b76d1d4ef2b6753f60d71dcee2a8715f0167adb75b5121f2fab60' 
  AND token = 'FRgVZkVyX7ptZaw4vSi6HLy2KV6T+3qFRksTwoEHrwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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