SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29c9694142b054a1cdf30088162816572fc9baacd0fc8c2caaf9dbf4213513e9' 
  AND token = 'MEsl5mGNHBLFTNnhP5MDDnxE/vBlYrAGPbzbdLDif5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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