SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '909252a345bccea397150ff3ec29787d5bd6220b04ea5c3a0f6e95298397c303' 
  AND token = 'KPIDHrbKfZjtwWC4QtlmLuzzImoNhl83XCGfPB/GgVA=' 
  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"
    }
  }
}