SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c66d7daa6c04aabb8df4d5e4db38b6f75171b925b57d2a2fb3f6f76331a023f0' 
  AND token = 'oUQ8X8VSYGXzpno4snVCOBqrPBe6RnfVjdMhttrScx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}