SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b855c77a6b5b6657aca6e0a52c820936cb4a445f13c0a23e123ec4be40836d5' 
  AND token = 'LrvKTOFW/UhaknAup/v6f/mqWcvdX+jVdtTN4V/aa1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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