SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b5f03b576a79383e92611390e951f57b6b5f4447f26bb236cc28444ed403dc3' 
  AND token = 'JiaMJr9QqP0WdNatEESlsFH4vdLawF1POvGa+JkxPlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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