SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '236e6001ff001a7dc9912396f1e35922c892b07cf8e1ecb6cb4364f465d6fa19' 
  AND token = '5GzxvqRvwMvjQWdXXgjR91hCdweIT8kr1i87haEcPlA=' 
  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"
    }
  }
}