SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb8f391f2f9ebab1a01fa10fa685e6c454107a6864b480b6a324ee3cb2bd4a01' 
  AND token = 'XKSoaFt/SpW4XPqYfBHu2n2ytIcgyDosH3/bj036ic8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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