SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69610011a826b6b3516d3d8f1f64e89c9d1235d80423a9a49e376817abd005a2' 
  AND token = '+tljN0+gnt/DuW45FrBZhwgj1Qoz6TjM2WUfegHedWc=' 
  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"
    }
  }
}