SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f43f973db6a0282ba4bdac71b51080ef362cb5a7d3a251e297343f7f511a0af5' 
  AND token = '4c6iY5bHC+1YVS+NKlsvwa1qi8Fh+BlJrRmru3fCJQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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