SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c71302c9bf98f814076d3f7855a54cb9707212fa74015cadb284ca954fa430' 
  AND token = '4tlXE16pRJk3EWutbKs8RhUkJu6b2LWYtkiCbPZCZRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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