SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2a78d92e41db09413c3754e732df6ac3431d2b0a3be4659c792e7d00a3c6662' 
  AND token = 'GHqNmPfzq7pZWgPB849/G5Fqk+QHplKgz6tadjIaaGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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