SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc1e39bb577bd35b5b00c8b10727a3b819e4501f38053724549bc5ed365edb49' 
  AND token = 'nUkPvi2iKaaKdTZkC4D2CQRzIfwpkP2jBmszweYH2eo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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